Effect of exogenous polyamine on polyamine and polyamine oxidase in Xiangzaoxian32 seedlings under osmotic stress were studied. The results showed that free PAO, bound PAO activities and Put, Spd, Spm contents increased under osmotic stress. Exogenous Put treatment significantly promoted free PAO, bound PAO activities and Put, Spd, Spm contents. Bound PAO activities were free PAO 9.8-15.65 times. Through relevant analysis, it showed positive correlation between Put, Spd, Spm contents an...